<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
<script>
    var num = 020;
    console.log(num);
    console.log(0.1+0.2);
    var result = "20";
    var aa = result - 10;
    console.log(typeof aa);
    console.log(aa);
</script>
</body>
</html>